Groucho Marx would not join any club that would have him as a member. By the same token, I always knew Facebook would become uncool the moment I joined. And lo, it has come to pass. According to Nielsen Online, the social network has suffered its first decline in the UK: the number of users fell from 8.9m in December to 8.5m last month.

Facebook was not originally for people like me, but for students. It started at Harvard and expanded via other elite universities. Facebook's explosive growth began when it opened up to everyone. Once your parents join, it becomes a less interesting place to hang out.

I joined last autumn simply to see some pictures of a friend's daughter's wedding. Now I have five Facebook friends. These include my two student children, who may regret having signed me up because I can see what they get up to.

Is Facebook's bubble bursting? It is not alone in its decline. MySpace's UK traffic fell by 5 per cent and Bebo's by 2 per cent, says Nielsen. Facebook's 712 per cent growth last year could not last. In part this is mathematical. Each new user adds friends, so it grows like a pyramid scheme. But eventually, the new friends added will be members already.

There must also be limits to the attraction of having Facebook friends, as opposed to real ones. It works within a defined group, where there are circles of acquaintances with experiences in common, but reading too much about people you barely know becomes a dull form of voyeurism.

Facebook's future could lie in the business market, where companies can now create pages for brands, products and services. A lot of companies block access to social networks, fearing time-wasting. This seems a poor strategy: if staff want to waste time, they will find plenty of other ways. But the more Facebook becomes something your boss, like your parents, approves of, its attractions may pall.

Grim down south

Fifteen per cent of southerners have never visited the north of England, while 10 per cent of northerners have never visited the south, says a report by the hotel chain Travelodge, which presumably has a close interest in persuading people to conquer their ignorance.

It also finds that three-quarters of the English are prejudiced against their northern or southern neighbours. So far, so stereotypical. Robert Sharpley, professor of tourism at the University of Central Lancashire, said the differences should be "celebrated".

We northerners have of course always been happy to celebrate our differences from those arrogant Sloanes in the south, but I am not sure whether that is what the professor has in mind.

I once heard Bill Tidy, the Merseyside-born cartoonist who created The Fosdyke Saga and the Cloggies, say the only way he would ever move south would be if the north was on fire. But he subsequently moved to the east Midlands, and I have lived in the south for more than half my adult life, so I should just shut my mouth.

Great band leader

I am pleased to see the Hallé Orchestra - celebrating its 150th anniversary - back among the world's great orchestras under Mark Elder, its musical director. Now it is breaking the glass ceiling by appointing its first female assistant conductor: Polish-born Ewa Strusinska will be the first woman to hold such a position in Britain. A colleague tells me a story from the Hallé's heyday under Sir John Barbirolli. At a function, a down-to-earth Manchester trade union official - the father of John Monks, former general secretary of the Trades Union Congress - proudly introduced the orchestra as "Mr Barbirolli and his band".

Booker of Bookers

The search is under way to find a Booker of Bookers to celebrate the literary prize's 40th anniversary. Yann Martel's The Life of Pi (2002) leads the betting, followed by Salman Rushdie's Midnight's Children (1981) and Michael Ondaatje's The English Patient (1992). My choice would be William Golding's Rites of Passage (1980), in which the great old man finally displayed a sense of humour.

Whodunnit

I spent the weekend near Marple, in the foothills of the Pennines. If it held a beauty contest, would the winner be known as Miss Marple?